About this 3D model

This is my servo linear actuator for general using.I used two gears for increase the range of linear motion. https://www.youtube.com/watch?v=eDrAxYOUAEM&list=UUnkxHXQOkr_G-Pm7oJrbaag&index=1 https://www.youtube.com/watch?v=nXXouUjZorY&list=UUnkxHXQOkr_G-Pm7oJrbaag&index=2